1. Field of the Invention
This invention relates to an automatic stopping device for a tape feeding apparatus for use with a tape recorder and the like.
2. Description of the Prior Art
An automatic stopping device for a tape feeding apparatus is already known which includes a capstan shaft, a reel shaft, a motor for normally rotating the capstan shaft and the reel shaft, and a switch operable upon stopping of rotation of the reel shaft for interrupting energization of the motor to stop rotation of the capstan shaft.
In such a conventional automatic stopping device for a tape feeding apparatus, the last end of a tape is detected by a detecting element which is urged to an operative position within a tape cassette in which it bends the path of a tape so that the tape may run along the bent path but is displaced from the operative position against the urging force by the tape when the tape is straightened by a tensile force of the tape exerted by a pinch roller and a capstan at the last end of the tape. In this manner, the detecting element mechanically detects the last end of the tape by its displacement from the operative position by the tape being straightened at the last end of the tape. Such a displacement of the detecting element is transmitted as a mechanical detection signal to turn a switch off to interrupt energization of a motor of the tape feeding apparatus. Then, after turning off of the switch, it is kept off by frictional forces of the motor, capstan shaft, pinch roller and so on.
Accordingly, the automatic stopping device operates regularly in a reproduction mode of the tape feeding apparatus in which the tensile force is continuously applied to the tape by the capstan against which the tape is pressed by the pinch roller. However, when the tape feeding apparatus is in a fast feeding mode, the automatic stopping device does not operate because the pinch roller is at a position spaced away from the pinch roller so that a tensile force sufficient to straighten the bent tape path against the urging force applied upon the detecting element is not applied to the tape at the last end of the tape. Consequently, in the fast feeding mode of the tape feeding apparatus, it is impossible to detect whether or not the tape is wound to its last end, and accordingly it is impossible to automatically stop feeding of the tape.
Further, if the motor, capstan shaft, pinch roller and so on are acted upon by vibrations or an impact, the frictional forces thereof may be decreased enough to cause the switch to be turned on. Therefore, the off position of the switch cannot be kept stably.
Besides, since the tape is fed along the bent path due to the detecting piece inserted in the tape cassette, the tape may be displaced in a widthwise direction by the detecting piece, which makes separation and prevention of crosstalk unstable.
In addition, if the tensile force of the tape is not sufficiently strong, then the switch will not be turned off. To eliminate this, the pressing force of the pinch roller against the capstan shaft may be increased to a sufficient level. However, this makes it necessary to exert a high operating force to move the pinch roller away from the capstan shaft.